LLVM-EXTRACT(1)

💅 LLVM-EXTRACT(1) — the llvm-extract page, bestie edition

okay so this is from the LLVM manual set — yeah, that LLVM — and it's the llvm-extract command. buckle up, she's a debugging icon ✨

🌸 NAME 🌸

llvm-extract — extract a function from an LLVM module 🫶

🎀 SYNOPSIS 🎀

llvm-extract [options] --func function-name [filename]

🦋 DESCRIPTION 🦋

so the llvm-extract command takes the name of a function and extracts it from the LLVM bitcode file you point it at. it's mainly a debugging tool, like literally its whole job is reducing test cases from bigger programs that are out here triggering a bug 😭 so you go from "huge messy program" to "tiny little reproducer" and honestly? slay.

and it's not just yoinking the one function — in addition to extracting the bitcode of the specified function, llvm-extract will also remove unreachable global variables, prototypes, and unused types. spring cleaning vibes 🧹✨

where does it read from? the llvm-extract command reads its input from standard input if filename is omitted, or if filename is -. and the output is always written to standard output — unless you use the -o option (see below, bestie, it's right there 👀).

✨ OPTIONS ✨

• --alias alias-name — extract the alias named function-name from the LLVM bitcode 👑 you can pass this multiple times to extract multiple alias at once.
• --ralias alias-regular-expr — extract the alias matching alias-regular-expr from the LLVM bitcode. every alias matching the regular expression gets extracted 💖 may be specified multiple times.
• --bb basic-block-specifier — extract basic block(s) specified in basic-block-specifier. may be specified multiple times 🔥 each <function:bb[;bb]> specifier pair will create a function. if multiple basic blocks are specified in one pair, the first block in the sequence should dominate the rest — no cap, that's the rule.
• --delete — delete specified Globals from Module 🗑️
• -f — enable binary output on terminals. normally, llvm-extract will refuse to write raw bitcode output if the output stream is a terminal 😤 but with this option, llvm-extract will write raw bitcode regardless of the output device. it's giving "i do what i want".
• --func function-name — extract the function named function-name from the LLVM bitcode ✨ may be specified multiple times to extract multiple functions at once. this is the main character option fr.
• --rfunc function-regular-expr — extract the function(s) matching function-regular-expr from the LLVM bitcode. all functions matching the regular expression will be extracted 🎯 may be specified multiple times.
• --glob global-name — extract the global variable named global-name from the LLVM bitcode 🌈 may be specified multiple times to extract multiple global variables at once.
• --rglob glob-regular-expr — extract the global variable(s) matching global-regular-expr from the LLVM bitcode. all global variables matching the regular expression will be extracted 💜 may be specified multiple times.
• --keep-const-init — preserve the values of constant globals 🍓 (don't let them get got).
• --recursive — recursively extract all called functions 🔁 like following the whole friend group, iykyk.
• -help — print a summary of command line options 🫶
• -o filename — specify the output filename. if filename is - (the default), then llvm-extract sends its output to standard output 💅
• -S — write output in LLVM intermediate language (instead of bitcode) 📝

---

⭐ EXIT STATUS ⭐

if llvm-extract succeeds, it will exit with 0 🎉 otherwise, if an error occurs, it will exit with a non-zero value 💀 no in-between, she's not subtle.

👀 SEE ALSO 👀

llvm-reduce(1)

🧚 AUTHOR 🧚

maintained by the LLVM Team — https://llvm.org/ — iconic behavior honestly 💖

🌸 COPYRIGHT 🌸

2003-2026, LLVM Project

---

and that's the whole page bestie 🎀 written up on 2026-10-06, tagged as doc source 23 for LLVM — go extract something cute, and remember: -o exists so you don't have to raw-dog your terminal 💅✨